OK, great news on winning the boat.
IRS matches the 1099Misc documents to your return, so it is very important the entire amount of the 1099Misc is reported on the return.
(I am assuming you won the boat due to your fishing activity).
You would show the income from the 1099Misc on your Sch C business for fishing.
Then for example if your 1099Misc is for $10K and the boat was sold immediately for $8K, you would show a $2K misc expense (which is a deduction).
This is effect is causing you to pay taxes on only the net ($8K in my example).
Due to this being somewhat unusual, make sure everything is documented very well, should a taxing authority (Federal or State) want to review this transaction.